Edible films serve several critical functions in food preservation,

including acting as a barrier to the migration of

moisture, oxygen, carbon dioxide, and volatile aromas.

Furthermore, these films can function as active packaging

by incorporating essential additives like antioxidants,

*Corresponding author.

E-mail address: mdabdelrazek.md@gmail.com, Abdelrazek_MD@yahoo.com

Received: 27/01/206 Accepted: 05/04/2026

Copyright @ Journal of Nuclear Technology in Applied Science (https://acspublisher.com/journals/index.php/jntas)

Mohamed A. Abdelaleem1, Entsar N. Mohamed2, Amira G.M. Darwish3,4 and Abeer M.F. Elbaz2

1Food Irradiation Unit, Plant Research Department, Radioisotopes Application Division, Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt.

2Food Engineering and Packaging Research Department, Food Technology Research Institute, Agriculture Research Center, Cairo, Egypt.

3Food Industry Technology Program, Faculty of Industrial and Energy Technology, Borg Al Arab Technological University (BATU), Alexandria, Egypt.

4Department of Food Technology, Arid Lands Cultivation Research Institute (ALCRI), City of Scientific Research and Technological Applications

(SRTA-City), Alexandria, Egypt.

antimicrobials, and flavoring agents, while simultaneously

enhancing the structural integrity and handling of the food

product (Zhu et al., 2011).

As a globally significant crop, the cucumber (Cucumis sativus

L.) is highly valued for its crisp texture and nutritional

profile. Despite its popularity, its high-water content makes

it extremely perishable and difficult to store for extended periods, even under refrigeration. Storage challenges are primarily driven by rapid respiration rates, chlorophyll degradation (yellowing), and significant moisture loss, which results in shriveling and increased susceptibility to microbial spoilage (Olawuyi and Lee, 2019).

Carboxymethyl cellulose (CMC) is an anionic polysaccharide synthesized through the alkalization of cellulose and a subsequent reaction with chloroacetate. This process introduces carboxymethyl groups at the C2, C3, or C6 positions of the glucose monomers, resulting in a molecular framework rich in hydroxyl groups that facilitate efficient water binding and absorption. The functional characteristics of the resulting polymer—such as its superior film-forming ability and moisture regulation—are primarily governed by its molecular weight, the degree of carboxylation per anhydroglucose unit, and the specific distribution pattern of carboxyl groups along the cellulose backbone (Ali et al., 2015). Due to its inherent biodegradability and non-toxicity, CMC is widely adopted for edible coatings, where it plays a pivotal role in maintaining the textural integrity of various food systems while supporting environmental sustainability (Li et al., 2008; Nie et al., 2004) and (Singh et al., 2019).

While radiation-processing technologies are well-established in various commercial sectors, their application in enhancing the functional properties of edible polymers—such as proteins and carbohydrates—remains an emerging field (Nelida Lucia del, 2016). Gamma irradiation is effectively utilized to induce the controlled degradation of bio-resources like chitosan, alginate, and cellulose, which aids in recycling and environmental mitigation. Once degraded by radiation, these carbohydrates exhibit significant biological activities, including antimicrobial properties and plant growth promotion, and can even serve as immune-boosting additives in animal and aquaculture feed (Makuuchi and Cheng, 2012).

The literature suggests that the synergistic use of edible coatings and gamma irradiation can significantly enhance the preservation of fresh produce. Building on this, the primary objectives of the current work were to evaluate the effects of a CMC/Glyc coating, modified by gamma irradiation, on the thermal behavior, physicochemical characteristics, rheological properties, and microbiological stability of fresh cucumbers, thereby extending their shelf life.

Edible coatings represent a versatile preservation strategy for fresh produce, functioning as a protective, semi-permeable membrane that modulates the internal microenvironment of the fruit or vegetable. By acting as a selective barrier, these coatings regulate the exchange of moisture, oxygen (O2), and carbon dioxide (CO2), which effectively slows the rates of respiration and dehydration. This physiological control is essential for maintaining structural and textural integrity, retaining aromatic volatile compounds, and inhibiting microbial proliferation, ultimately extending the shelf-life of the produce by defending against multiple forms of degradation (Lee et al., 2003).Fourier Transform Infrared )FT-IR( Spectral analysis of CMC/Glyc solution

Fourier transform infrared (FTIR) spectral analysis of the carboxymethyl cellulose (CMC)/glycerol edible solution identifies the key functional groups of the composite matrix while demonstrating the structural modifications induced by low-dose gamma irradiation (0, 1, 2, and 3 kGy). A broad, intense absorption band spanning 3000–3600 cm-¹ is assigned to the stretching vibrations of free as well as intra- and intermolecularly hydrogen-bonded hydroxyl (–OH) groups, which are derived from both the hydrophilic CMC polysaccharide framework and the glycerol plasticizer (Zaïdi et al., 2011). The dual peaks resolved near 2928 cm-¹ and 2880 cm-¹ signify the asymmetric and symmetric aliphatic C–H stretching vibrations of the –CH₂ and –CH₃ groups within the CMC polymer backbone and plasticizer (Glycerol). Furthermore, the sharp peak at 1591.60 cm-¹ in the unirradiated control solution serves as a characteristic marker for the asymmetric stretching of carboxylate anions (–COO-) in sodium CMC, while the adjacent peak at approximately 1412 cm-¹ corresponds to their symmetric stretching vibrations (Gupta et al., 2019), thereby confirming successful carboxymethyl substitution along the cellulose chains. Finally, the prominent, sharp band centered at 1028.77 cm-¹ in the control sample reflects the C–O–C stretching of the glycosidic and ether linkages in the polysaccharide framework, overlapping with the C–O stretching of the primary and secondary hydroxyl groups of glycerol (Vidal et al., 2020; Gad et al., 2021).

As shown in Figure 1,the main peaks in the control solution (0 kGy) show relatively lower transmittance values (higher absorption intensity). Upon exposure to 1 kGy and 2 kGy, the overall transmittance profiles increase noticeably (e.g., the –OH valley shifts upward). This indicates a reduction in the density or vibrational efficiency of these specific bonds. The –OH band shifts downward from 3282.97 cm-¹ in control solution to 3274.22 cm-¹ in irradiated solution at 1 kGy, implying a slight reorganization of the remaining hydrogen bonding configurations or changes in the plasticizer-polymer affinity. Interestingly, at 3 kGy, the spectrum displays a reversal in the trend. The transmittance of the main bands decreases again (e.g., the –OH valley drops, and the C–O–C peak intensity enhances significantly compared to the 1 and 2 kGy).

As with other polysaccharides, however, CMC can still undergo chemical modification when subjected to radiation. Thus, the FTIR data confirms that the irradiated solutions retain their primary functional groups (–OH, –CH, and C–O). However, the subtle shifts in the peaks between all solution samples suggest that the irradiation treatment likely caused minor changes in the molecular environment or hydrogen bonding intensity within the solution matrix (von Sonntag, 2003).

Thermogravimetric analysis (TGA) is an essential tool in materials science for evaluating sample purity and thermal endurance. In this study, primary TGA thermograms were analyzed to calculate key kinetic parameters, including the reaction order and activation energy of thermal decomposition. Furthermore, TGA was employed to experimentally assess the thermal stability of CMC/Glyc blends. The initial TGA thermograms for CMC/Glyc solutions, both before and after irradiation, are presented in Figure (2-A). Based on the weight-loss percentages recorded up to 491°C (Table 1), the irradiated samples exhibited greater thermal resistance than the unirradiated controls, particularly above 300°C. in addition, the control samples (0 kGy) showed superior stability below 100°C, samples irradiated at 2 kGy show a stabilizing effect compared to the other irradiated doses. At 400°C and 491°C, the 2 kGy sample retains the most residual mass (25.5% remaining, or 74.5% loss). This suggests that at this specific dose, radiation-induced cross-linking may predominate over chain scission, creating a slightly more robust charred residue that resists further breakdown. In addition, enhanced thermal resistance at elevated temperatures (up to 491°C) and reinforce the polymer matrix against high-heat decomposition and irradiation treatments strengthen the material’s structure. In the other hand, 3 kGy dose consistently exhibits the highest weight loss across all temperature levels (e.g., 72.55% at 300°C and 81.69% at 491°C). This indicates that higher levels of radiation likely induce chain scission within the polymer, breaking down the molecular weight and making the material more susceptible to thermal degradation. These findings align with previous research by (Abdel Ghaffar et al., 2019), (Abdel-Ghaffar and Ali, 2022), which indicated that thermal stability typically increases in correlation with higher irradiation doses.

Furthermore, (Ali et al., 2015) found that the thermal stability of bioblend CMC/TiO2 increased with increasing the irradiation dose up to (10 kGy). A sort of crosslinking process occurred after irradiation treatment of CMC, that increase thermal stability in pure CMC (Senna et al., 2000), (Ibrahim et al., 2013) and (Ibrahim et al., 2014).

Differential scanning calorimetry (DSC) technique is one of the convenient methods for investigating the compatibility of polymer blend. Figure (2-B) show the DSC thermograms for CMC/Glyc at different gamma irradiation doses (1, 2 and 3 kGy). The DSC curve shows two endothermic (water removal) peaks; at 57.03, 60.31, 59.22 and 63.81°C for 0, 1, 2 and 3kGy, respectively which are ascribed to moisture evaporation, and another endothermic peaks; at 307 °C (from 251.5 to 362.5 °C), 298.95 °C (from 261.27 to 336.63 °C), 300.06 °C (from 271.37 to 328.75 °C) and 296.44 °C (from 266.35 to 326.53 °C) for 0, 1, 2 and 3 kGy, respectively which is attributed

to the dehydration/decomposition of CMC. This behavior is associated to the complete decomposition of CMC, leading to a minute solid residue (El-Sherbiny et al., 2009). Moreover, as shown in Figure (2-B), the 2 kGy dose shows a unique profile, where the exothermic (decomposition) peak appears slightly broader and less sharp than the 1 kGy dose. This likely reflects the “sweet spot” identified in the TGA analysis, where a balance of radiation-induced cross-linking provides a more stable thermal response before further degradation occurs at higher doses. On the contrary, at 3 kGy, the exothermic peak begins to flatten and shift slightly to the left (lower temperature). This is indicative of polymer chain scission, where the radiation has broken enough glycosidic bonds to lower the thermal threshold required for decomposition, leading to the lower thermal stability observed at the highest dose. Our finding is in agreement with (El-Sakhawy et al., 2019) who found that CMC have two endothermic curves. In the contrast with unirradiated CMC/Glyc, the maximum melting temperature (Tm) 307 °C, shifted slightly to the left after irradiation treatment. Where Tm values were 298.95, 300.06 and 296.44 °C for 1, 2 and 3 kGy, respectively. Irradiation of CMC/Glyc shows a narrow endothermic band, probably attributed to the higher thermal stability of CMC.

Thermomechanical Analysis (TMA) in Figure (2-C) revealed that irradiation doses up to 3 kGy significantly impact dimensional stability. The consistent decrease in sample thickness (μm) during heating suggests that thermal energy triggers internal stress relaxation or further structural reorganization, such as cross-linking, across all irradiation levels (García et al., 2009) and (James, 2017). Based on the thermograms provided, the dimensional changes of all samples under a constant load of -5.0 g across a temperature range of roughly 25°C to 125°C, can be observed. Across all four irradiation doses (0, 1, 2, and 3 kGy), the curves exhibit a consistent downward trend, indicating compression or softening of the material as temperature increases. Sample irradiated with 3 kGy, shows the largest displacement (53 μm), which could indicate that higher doses are inducing chain scission, leading to a more “relaxed” or softer matrix that compresses more easily. On the other hand, lowest irradiation dose (1kGy) shows the smallest total displacement (28 μm), suggesting that low-dose irradiation might have enhanced the structural rigidity, possibly through localized cross-linking

Table 1. Effect of irradiation dose on thermogravimetric properties of CMC/Glyc

Table 1. Effect of Irradiation Dose on Thermogravimetric Properties of CMC/Glyc

Vitamin C content

Vitamin C is a vital water-soluble antioxidant that mitigates damage from reactive oxygen species in various produce, including citrus, guava, and cucumber (Lester, 2006). Figure (3-A) illustrates the fluctuations in Vitamin C concentration throughout the storage period. Our findings indicate a significant interaction (p ≤ 0.05) between storage duration and the type of edible coating applied. Specifically, cucumber coated with unirradiated CMC/Glyc showed a rapid loss of Vitamin C, whereas those treated with irradiated coatings exhibited a more gradual decline. Overall, the irradiated coatings significantly improved Vitamin C retention, with the 3 kGy treatment proving most effective across all samples.

The pH values for uncoated and coated fresh cucumber stored at room temperature are presented in Figure (3–C). Non-significant differences in all samples coated with irradiated CMC/Glyc solution during storage period. A slight non-significant decrease in pH values showed in all irradiated samples after 12 days of storage. The observed decrease in pH may be attributed to the semi-permeable CMC/Glyc film formed on the fruit’s surface. This barrier likely modified the internal atmosphere by altering endogenous CO2 and O2 concentrations, which subsequently delayed the ripening process. Conversely, Oluwaseun et al. (2013) reported a slight increase in the pH of cucumbers coated with CMC/Glyc by the conclusion of a seven-week storage period.

The results revealed that total soluble solids (TSS) remained statistically similar (P ≥ 0.05) across all treatments, including the control, during the initial seven days of storage. However, following this period, samples coated with the unirradiated CMC/Glyc solution experienced a significant decline (P ≥ 0.05) in TSS levels. In contrast, cucumbers treated with irradiated coatings (1, 2, and 3 kGy) maintained more stable TSS concentrations throughout the remainder of the study (Fig, 3–D). In the control samples (unirradiated CMC/Glyc), total soluble solids (TSS) declined to 8% by day 14, reaching a minimum of 7.6% by the end of the 21-day period. While a general reduction in TSS was observed across all treatments as storage progressed, the decrease was notably less pronounced in samples treated with irradiated CMC coatings. This preservation of soluble solids is likely due to the synergistic effect of irradiation and CMC, which delays fungal proliferation and slows physiological processes such as respiration, transpiration, and senescence (Vachon et al., 2003). These findings align with (Dong and Wang, 2017), who noted that stable TSS levels in coated cucumbers result from the inhibition of respiratory and metabolic activities.

In contrast, (Özden et al., 2002) noted that a decline in soluble solids during storage is a natural phenomenon. This occurs because sugars—the fundamental component of a product’s soluble solid content—are gradually depleted through respiration and the ongoing metabolic requirements of the cucumber samples.

The firmness of all the coated cucumber decreased gradually during the 21 days of storage (Figure, 3–E). In all irradiated CMC/Glyc-coated samples a slight decrease of firmness was observed during the duration of storage - which was similar to the above results for weight loss - compared to control samples. This phenomenon can be attributed to the interaction between storage duration and the application of irradiated coatings. A parallel trend was noted in mass loss, where cucumbers treated with these specific solutions showed minimal fluctuations. It is suggested that the limitation of moisture loss was the primary mechanism allowing coated samples to maintain greater firmness compared to the control. This reasoning aligns with the findings of (Aguirre-Joya et al., 2017), who established that moisture loss is directly correlated not only with mass reduction but also with the rate of fruit softening.

Figure (4) presents the flow and viscosity curves for all evaluated samples. The flow behavior, illustrated in Figure (4-A), depicts shear stress as a function of the shear rate. As the shear rate increases, a corresponding continuous rise in shear stress is observed for the CMC/Glyc solution. Notably, the curves for the upward and downward shear rate sweeps almost entirely overlap, indicating that the CMC/Glyc system possesses excellent structural recovery under external mechanical stress. Furthermore, a progressive increase in irradiation dosage results in a gradual reduction in the shear stress of the solution.

Flow behaviour shown in Figure (4–B) represents the impacts of irradiation treatment on the apparent viscosity of CMC/Glyc solution as a function of shear rate, where apparent viscosity initially decreased rapidly as the share rate increased and then stabilized in all samples. Rheological properties of CMC/Glyc suspensions exhibit viscoplastic behaviour (Jankowska et al., 2023) (Salehi et al., 2023).

Exposing the CMC/Glyc solution to irradiation results in a reduction in viscosity. To enhance the flexibility of the resulting edible films, glycerol is incorporated as a stable, non-toxic plasticizer. These plasticizers are essential for reducing stiffness and increasing film elasticity; however, they can also elevate the water vapor permeability of the material (Sobral et al., 2001).

The reduction of viscosity behaviour was observed at all dose levels leading to a greater reduction in the viscosity. The results demonstrated that the average apparent viscosity of CMC/Glyc solution decreased from 1.2 to 0.26 Pa.sec in control samples (0 kGy). While the values of viscosity of irradiated samples at doses from 1 - 3 kGy decreased from 1 to 0.19 Pa.sec, 0.75 to 0.12 Pa.sec and 0.48 to 0.08 Pa.sec, respectively.

The observed modifications in viscosity following irradiation can be attributed to the cleavage of glycosidic bonds within the cellulose backbone. Importantly, this structural degradation occurs without altering other functional groups (Suljovrujić et al., 2007) (Choi et al., 2008). Radiation processing is a common technique for synthesizing CMC-based hydrogels (Fei et al., 2000). Research suggests that radiation-induced cross-linking in CMC is often more efficient than traditional chemical methods, though achieving high cross-linking density may require substantial radiation doses. It is critical to note that in all irradiated materials, cross-linking and degradation occur simultaneously as competing mechanisms (Wach et al., 2003).

The fluctuations in total bacterial count (TBC) and mold and yeast count (MYC) for both coated and uncoated cucumbers are illustrated in Figure 5(A and B). During the first week of storage, the initial bacterial load in the control samples (unirradiated CMC/Glyc) was 6.2 log CFU/g, whereas samples treated with the 3 kGy irradiated coating exhibited a significantly lower load of 2.71 log CFU/g. This trend is consistent with findings reported by Olarte et al. (2009) regarding broccoli. By the third week, the TBC for control cucumbers reached 9.84 log CFU/g, while the irradiated treatment limited bacterial growth to 6.23 log CFU/g. These data demonstrate that the irradiated CMC/Glyc solution functions effectively as both an edible coating and a potent antimicrobial agent.

The enumeration of yeasts and molds is a critical quality indicator for fresh produce, as fungal decay represents a primary factor limiting shelf life and commercial distribution. As shown in Figure (5), the application of CMC/Glyc coatings significantly reduced (p < 0.05) microbial populations compared to uncoated controls. Specifically, the initial mold and yeast count (MYC) in control samples was 4.53 log CFU/g during the first week, whereas samples treated with 3 kGy irradiated coatings exhibited a reduced load of 2.82 log CFU/g. Throughout the storage period, the irradiated CMC/Glyc coating successfully inhibited fungal proliferation, maintaining a final count of 7.34 log CFU/g compared to the significantly higher 9.62 log CFU/g observed in in controlling spoilage is likely due to its ability to act as a gas barrier, thereby establishing a modified atmosphere that preserves the fruit’s integrity (Dutta et al., 2009).

Furthermore, the decrease of microbial count in coating with irradiated CMC/Glyc solution is probably due to antimicrobial effect of degradable biological compounds after irradiation treatments where, (Makuuchi and Cheng, 2012) found that irradiation of carbohydrates polymers like CMC, present biological compounds that have antimicrobial activity.

In conclusion, this study demonstrates that gamma irradiation significantly enhances the functional performance of CMC/Glyc edible coatings for cucumber preservation. This modified coating effectively establishes a semi-permeable atmosphere that suppresses respiration, minimizes weight loss, and maintains total soluble solids. Most notably, the 3 kGy treatment provided the most robust antimicrobial defense, significantly reducing both bacterial and fungal proliferation. While, thermal analysis (TGA and DSC) identified 2 kGy as the optimal dose for enhancing thermal stability, likely due to radiation-induced cross-linking that outweighs chain scission at this specific level. Collectively, these findings suggest that irradiated CMC/Glyc coatings offer a synergistic approach to extending the shelf-life and maintaining the post-harvest quality of fresh produce.